package Temp.杂乱无章;

import java.util.Scanner;

public class 整数求和 {
    public static void main(String[] args) {
        int sum = 0;
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        for(int i=1; i<= n; i++){
            sum+=i;
        }
        System.out.println(sum);
    }
}
